Multiple layered adhesive tapes for sealing carton flaps either during or after manufacture are well known in the art. Applicant is the inventor of two such tapes, disclosed and claimed in U.S. Pat. No. 4,041,202 issued Aug. 9, 1977 and in U.S. Pat. No. 4,351,877 issued Sept. 28, 1982. U.S. Pat. No. 4,041,202 solved problems in the prior art and provided a delamintable tape which could be stripped away to leave two lateral portions of a bottom layer separated on the two side of a joint thereby to release the pieces being joined.
Similarly, U.S. Pat. No. 4,351,877 solved problems in the prior art and provided a strippable laminated tape by utilizing a plastic layer for strength and a thin carrier layer to hold the adhesive. The carrier layer is made of low internal bond paper which separated when the plastic layer was pulled, leaving a thin easily breakable layer.
In the prior art, multiple layered tapes have not solved the problem of markability on the face of the tape. Single layer Kraft tapes are markable, but do not provide strength needed for certain applications. If a fiber reinforcing layer is provided, there is difficulty in attaching a Kraft face to the rough and uneven surface of the tape. Further, because of the unevenness of the fibers, substantial adhesive would be required to secure a Kraft face to the fibers. Finally, because the Kraft paper face is of substantial thickness, it, along with the already heavy fiber, makes the tape thicker, thus making the tape rolls larger and more difficult to store, inflexible, and costlier.
Because of these problems with using fibers to provide strength, many tapes now utilize a plastic layer. The plastic layer simultaneously solves the problem of strength and thickness. However, the plastic layer, when used on the tape face, does not provide a suitable surface for marking with pen, pencil, inked rubber stamp or the like.
It is generally difficult to print on a plastic faced tape. Pre-printing on the plastic face of the tape is costly since a special printing process must be used. Applicant's own U.S. Pat. No. 4,351,877 may have messages pre-printed on the carrier layer prior to manufacture of the tape with the pre-printed message showing through the clear plastic face of the tape. However the message desired must be determined prior to the manufacture of the tape. An inventory of tapes with many possible messages must be accumulated. Further, if a customized message is desired, such as a company name, the entire tape must be manufactured.
Another problem with plastic faced tapes is the adhereability. Adhesives which are suitable for sticking to plastic-faced tapes are generally known in the art. If the adhesive is not water soluble, then it must be preapplied to the label or tag in a tacky condition. By using a non-water soluble adhesive, the labels or tags are generally more expensive. Further, labels, stamps, etc., which have a water soluble adhesive, must be carefully placed so that they are not on top of the plastic face of the tape. This is a serious disadvantage if a significant number of cartons are labeled because of reduced productivity and efficiency.
An inherent problem with plastic faced tapes is that they are not easily self-adhereable (i.e. the tape cannot adhere to the top of itself). Plastic faced tapes with a water based gumming layer, such as applicant's own U.S. Pat. No. 4,351,877, provided a strippable thin tape, but did not solve the problem of self-adhereability.
Non-self-adhereable tapes have several disadvantages. First, if a carton is to be completely wrapped with tape around the circumference of a carbon, non-selfadhereable tapes would have to be carefully cut so that no overlap would occur. If the tape could be overlapped there is added strength, thus reducing the possiblity of carton breakage. Overlapped tape will also provide a continuous seal to keep foreign objects out of the interior of the box. Additionally, a non-self-adhereable tape cannot be criss-crossed on the carton for additional strength.
Accordingly, applicant has solved these problems. Applicant has combined the advantages of a plastic strength layer tape with the advantages of a paper tape. By uniting a thin low bond paper on one face of the plastic layer, a permeable outer surface is provided. The permeable layer may be colored, thus providing an aesthetically pleasing tape. Also, the tape may be written on by pen, marker, or the like for addresses or for stamping of messages. This permeable surface can be used for pre-printed messages, such as "Handle with Care", or "Fragile" so that the tape serves not only to seal a carton but to communicate a message. The tape can be manufactured prior to choosing the desired message, and then stored, thus minimizing the inventory needed.
The permeable layer also provides a suitable surface for gluing on stamps, labels or the like. The surface is suitable for both water soluble and non-water soluble adhesives This allows less costly labels with water soluble adhesive to be used. Further, the labels and stamps need not be carefully placed thus reducing the time needed for carton preparation.
This novel tape is also self-adhereable. A water soluble gumming layer is used for applying this tape to a carton or the like. The tape may be overlapped on the carton by sticking the gumming layer to the permeable layer. This overlapping of the tape provides additional strength to reduce carton breakage, and a continuous seal.
Applicant's tape also incorporates the advantages of applicant's prior invention in U.S. Pat. No. 4,351,877. The plastic layer provides strength for the tape and at the same time is thinner, smoother, more flexible, and less costly than a fiber reinforced tape. By covering the plastic with a permeable layer, the disadvantage of plastic's water resistance is overcome by the presence of the permeable layer. Applicant has also incorporated features by use of a carrier layer adhering to the plastic layer. First, the carrier layer provides a surface to "carry" a water soluble adhesive for sticking to the carton. Second, the carrier layer may be made of low internal bond which separates internally when the stripping of the upper strength layer.
In applicant's alternative embodiment the carrier layer and the permeable layer are interchanged. Because the permeable layer is thinner than the carrier layer, less adhesive will be used for the water soluble adhesive layer. Second, since the carrier layer is thicker than the permeable layer, printing or writing on the face of the tape will be better absorbed. Finally, by placing the carrier layer opposite the water soluble adhesive, the tendency of the tape to curl when wet is reduced.